This study advances the understanding of the role of organizational variables in the successful delivery of residential substance abuse treatment protocols. The importance of understanding the organizational features essential to the success of these programs is evident in: (a) the DATOS study finding of great variability in outcomes among residential substance abuse treatment programs, (b) the rapid expansion of residential programs to serve new populations, and (c) changes demanded by third-party funders of these programs. A key organizational variable is internal agreement among clinical director, professional specialty staff, primary treatment staff and clients, about the treatment goals and elements needed for treatment success. According to the formulation, agreement consists of two variables, concordance (Cc: defined as the level of agreement between different groups in an organization, such as administrators, staff, and clients) and consensus (Cs: defined as the level of agreement within these groups). Together, these variables determine the extent of coordinated effort in implementing the treatment protocol. The two variables differ in that high levels of concordance between groups cannot occur without high levels of consensus within the groups, but high levels of consensus can exist without correspondingly high levels of concordance. When Cc is high across all organizational groups, adherence to the prescribed treatment protocol is high. The study investigates a model in which: i) organizational contextual variables (e.g., size of the organization, staff-to-client ratios) affect communication, participation in decision-making and constructive conflict; ii communication, participation in decision-making, and constructive conflict affect Cc and Cs; and iii) Cc and Cs each affect treatment success, measured in terms of staff and client satisfaction, client engagement in treatment, and retention. Aims include 1) determining the relationship between Cc and Cs; 2) identification of the organizational correlates of Cc and Cs; 3) determination the relationship of Cc and Cs with treatment success; and 4) determination of the relationship between client, staff, and program characteristics on the success of residential treatment programs.